Imparting a color change or color effect on hair can be done using permanent and semi-permanent or temporary hair coloring products. Conventional permanent hair coloring products are dye compositions comprising oxidation dye precursors, which are also known as primary intermediates or couplers. These oxidation dye precursors are colorless or weakly colored compounds which, when combined with oxidizing products, give rise to colored complexes by a process of oxidative condensation. The oxidizing products conventionally use peroxides such as hydrogen peroxide as oxidizing agents. Such permanent hair color products also contain ammonia or other alkalizing agents such as monoethanolamine (MEA) which causes the hair shaft to swell, thus allowing the small oxidative dye molecules to penetrate the cuticle and cortex before the oxidation condensation process is completed. The resulting larger-sized colored complexes from the oxidative reaction are then trapped inside the hair fiber, thereby permanently altering the color of the hair.
It is also known that it is possible to vary the shades obtained with the primary intermediates by combining them with couplers or coloration modifiers. The variety of molecules used as primary intermediates and couplers can allow a wide range of colors to be obtained.
The artificial color of hair treated with a permanent hair coloring product does not easily wash out during the course of routine shampooing. The colorations obtained show good longevity (also referred to as color-fastness) with exposure to shampoo.
It has been surprisingly found that by employing a method of coloring keratinous substrates involving the steps of applying a color base composition containing at least one primary dye intermediate onto hair, followed by application of a developer composition containing at least one oxidizing agent chosen from persulfates, perborates, percarbonates, and salts thereof, onto the hair, either immediately after, or at any time thereafter that is convenient to the consumer from the time of application of the color base composition, for example up to 60 minutes thereafter, the following several significant advantages can be realized, as compared to the use of conventional permanent dyeing techniques: shorter dyeing time; comparable color-fastness to conventional permanent hair dyeing methods using peroxide developers; improved color deposit on the hair; little to no odor. In some instances, depending on the oxidative dye and/or coupler molecule used, different colors/shades may be obtained compared to the conventional hair coloring compositions/methods using peroxide developers.
Another disadvantage associated with the use of conventional permanent hair dye formulations and systems is that they are very messy to apply and have a tendency to cause scalp staining.
Thus, it is also an object of the present invention to provide a means of permanently coloring hair in a less messy or more clean manner.
Another object of the invention is to provide a permanent hair coloring system that does not lift the color of the hair, that is, it does not lighten hair color but is still able to vary the tone of the hair color or make the hair color darker. Lifting is defined as the process by which the natural hair melanin is removed. The alkaline environment ensures that the cuticles of the hair are opened to allow penetration of an oxidizing agent, such as hydrogen peroxide. Such an oxidizing agent breaks down the melanin by providing it with oxygen, and the melanin molecule is colorless when oxidized. This leaves the hair lightened from its natural color.
Another object of the present invention is to provide a means of permanently coloring hair in the absence of peroxide raw material ingredient.